build_reloc.sh: rename relocatable packages
build_reloc.sh: rename relocatable packages

Currently, we use following naming convention for relocatable package
filename:
  ${package_name}-${arch}-package-${version}.${release}.tar.gz
But this is very different with Linux standard packaging system such as
.rpm and .deb.
Let's align the convention to .rpm style, so new convention should be:
  ${package_name}-${version}-${release}.${arch}.tar.gz

See scylladb/scylla#9799

Closes #185

scylladb/scylla-jmx,scylladb/scylla-jmx,scylladb/scylla-jmx